The present invention relates to well servicing fluids. More specifically, the present invention relates to a composition and method for effecting sealing, grouting or plugging in earth boreholes.
Other than oil and gas wells, there are numerous instances where it is necessary to effect sealing in certain areas in drilled earth boreholes. Such boreholes occur, for example, in water well drilling, in observation holes for construction and engineering purposes such as hydrology studies, in mineral exploration boreholes and in seismic shot holes. For example, it is common practice in the case of water wells to grout or seal well casing by filling the annulus between the casing and the wall of the borehole. Additionally, it is often necessary when an earth borehole is abandoned to plug it to prevent the commingling of aquifer(s) water and/or to prevent entry of contaminants from the surface.
Heretofore, casing sealing and grouting, and plugging, has been accomplished by cementing techniques which are expensive, not always effective, and generally not usuable with plastic casing due to the heat evolved when the cement is setting causing the casing to deform. It has also been common in such sealing or grouting, as well as in hole abandonment procedures, to use slurries of water swellable clays, e.g. bentonite; however, the use of water swellable clays is disadvantageous in that, since the clays tend to swell almost immediately when placed in water, particularly if subjected to any shearing such as will occur during pumping, only a relatively low level of solids can be carried in the slurry to the site in the borehole where the sealing is to be carried out.